simulation of geothermal district heating systems

simulation of geothermal district heating systems

@
THE UNITED NATIONS UNIVERSITY
ORKUSTOFNUN
NATIONAL ENERGY AUTHORITY
SIMULATION OF GEOTHERMAL
DISTRICT HEATING SYSTEMS
Ism ail Dokuz
Geothermal Training Programme
Reykjavik, Iceland
Report 3, 1988
Report 3, 1988
SIMULATION OF GEOTBBRMAL DISTRICT BEATING SYSTEMS
Ismail Dokuz
UNU Geothermal Training Programme
National Energy Authority
Grensasvegur 9
108 Reykjavik
ICELAND
Permanent Addre ss :
Mineral Research and Exploration General
Directorate, Drilling Department
MTA, Ankara
TURKEY
ABSTRACT
District heating systems are preferable compared to
individual heating systems as the heating method is
economical, safe and less pollution. Fossil fuels have been
used in most of the district heating systems but nowadays
geothermal energy is being used in many systems where
geothermal energy is available.
Simulation methods enable us to follow behavior of the flow
as well as indoor temperature in each building and pressure
at every point in the system on hour by hour basis and hereby
determine system behavior both during cold waves, and also
over long periods of time. In order to use these simulation
methods on a district heating system, a fictitious town has
been made, and is chosen to be located somewhere in Turkey .
The buildings are assumed to be built according to usual
Turkish construction methods.
Weather data for this fictitious town is simulated by using
temperature variations of the year 1981 in Reykjavik added to
the average climate of Denizli, Turkey.
This study is based on the Icelandic method of the design of
geothermal district heating systems. However the real
weather data from Turkey has been used to evaluate the heat
loss of the model building and the heat load of the simulated
district heating model network.
ii
CONTENTS
Abstract ...••••. .. .. ...........................• • • .... ..•. i i
Tables. • • • . • • • . • • . • • . . • • . . • • . • • • . • • . • • . . • • . • . • . • • . . • . • . • • •
v
Figures ...... ..................... . .. . .. . .. . .. . ..........
v
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The scope of the work... . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
1
The Purpose of the study. .. .. .. . ..... ... .............
Theoretical background of the district heating simulation.
Introduction. . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . .
Design demand based on type of buildings .•.•.. • . • •. • .
Design demand based on annual fuel consumption •.••. • .
Weather conditions .. .. . .. .. .. .. . ..... . .... . ..........
2
3
3
3
4
4
Cooling of buildings during cold waves.......... ....
Approximation of cold waves..... . .. .. . . .............
Evaluation of the building parameters . .. . •••. .•.•.. •
Heat loss calculation for the model building ..•.•..•.....
Introduction. . • . . . • . . . . . . • . . . . . . . . . . . . . . . • . . . . • . • • . •
Description of the model building .. • .. • .. • .• ..•... . .
Heat loss calculation based on TS 825 .•.••.•.•• . •.••
Building heat loss parameters ..•..•.....•..•.•..•.••
Description of the district heating model system ..•.••.•.
Introduction. • . . • . . . . . . . . . . . . . . • . . . . . . . . • . • . . • • • . . • .
Weather conditions...... . .. .. ......... ........ ......
Evaluation of the system design tempera ture ..•.•..••
Simulation of the model district heating system • .. • .•..•.
Introduction . . . • • . . • • . . • . . . . . . . . . • . . . . . • . . • . • . . • . • . .
Description of the work •. .. ...•.••••• .. •• . . . • ..•.•..
Simulation of the system ...•.. • •••..... • •••••..•.•..
Conclusions. . • . . . • . . • • . . • • . . • • . • . . • . . . • • . • • . • . . • . . . . • . • • .
Acknowledgements. • • • . • • • • • • • • • • . • • • • . . . . . . . . • . . • . . . . • . . • .
Nomenclature. • . . . . . . .• . . •• . . • . . . . . . • . . • . . . . . . . . • . • . . • . • . .
References. . • • . . • • . . • . . . • . . • • . . • . . . . . . • . . • . . • • • . . • . • . . • . •
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iii
TABLES
Table 1 - Characteristic values for an average one
story building Icelandic home • . .•. . • . • .. • . •• . ••
Table 2 - The characteristic values at 20 ' C for
the model building. . ... . ... . .... . ............. .
31
32
Table 3 - Evaluation of building parameters for the model
building at outside temperature o f -7 · C • . .•.• .
33
Table 4 - Weather data for Denizli, Turkey . .. • .•.. • . • •. •
34
Table 5 - Summary of the pipe system design . . . • • • . . •. • •. •
35
PIGtlRES
Figure 1 - Observed temperatures in Reykj avi k during
a severe cold wave .. .. . .. .. . . ... . . . . . . . . . . . . .
Figure 2 - Cold wave approx imation. .. .. . . ..... . .. . . . . .. .
Figure 3 - Climate zones in Turkey. .. . .. . . . .. .. . ........
Figure 4 - Plan of the model building layout .. .... . . . . . .
Figure 5 - Layout of the model system.. . . ... . . . ....... . .
Figure 6 - Weather data-actual minimum, ma ximum, average
v alues for Denizli , Turkey together with
simulated temperature . .. . .. . .. ... .. .. . . ......
Figure 7 - Temperature variation during a cold wave .....
Figure 8 - Shematic of the simulated model system..... . .
Figure 9 - System mass flows . ...... . . .. .. . .. . . . ....... . .
Figure 10- Simulated system pressures.... ....... . . . .. . . .
Figure 11- Simulated indoor temperature for 90/ 70
systems. . • • . . • • . . • . . . • . . • • . • • . . . . . . . • . • . . • . • •
Figure 12- Simulated indoor temperature f or 80/ 40
systems.. . .. . ... . ....... . . .. . . . . . .... . .. ... ..
iv
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47
INTRODUCTION
The scope of the Work
A district heating system is defined to be a system where a
number of buildings are heated from a central heating plant.
Although conventional fuels are frequently used in the
heating plant,geothermal energy is increasingly being used in
district heating systems in many countries in the world where
geothermal energy is available. Many geothermal district
heating systems are being operated in the U.S . A. , Hungary,
the U.S . S.R., France, New Zealand, Italy, J a pan and Iceland
(Diamant and Kut,1981).
When the temperatures of the geotherrnal fluids are higher
than the minimum supply temperatures in the heating
application it is possible to supply all of the heating
demands of some group of users (Harrison, 1987).
Determination of the design of the district heating systems
depend on calculation of minimum heat load , maximum heat load
and estimated annual heat load. During the operation of the
district heating systems external heat load and internal heat
load are time dependent. To evaluate the changing
relationship between internal and external heat loads
simulation methods are employed.
This work has been carried out during the UNU Geothermal
Training Program as a finally report. The author has been
taking a number of lectures on geothermal energy and he has
been concentrating on the Reykjavik District Heating System
as a special study topic.
There are several methods for calculation of heat load of the
buildings and the system design temperature. In this work
calculation of the heat loss of the building is based on TS
825 (Turk Standardlari, 1985) and the Karlsson method
(Karlsson, 1982).
1
The main parts of the report as follows:
1. Discussion of theoretical background for district heating
simulation .
2. Selection of a typical Turkish building and evaluation of
its heat loss.
3 . Definition of a fictitious district heating system and
creation of suitable weather data.
4. Simulation of the district heating system in fictitious
town in Turkey, and study of its response to a cold wave.
The Purpose of the study
During the operation of the district heating systems,
external heat load and internal heat load are time dependent
and depend on the weather conditions and operating
conditions .
To calculate heat load is very time consuming in large scale
district heating system. When planning the connection of
premises to a district or group heating network, the heat
requirements of the premises must be accurately established.
It is necessary to establish the maximum heat demand, the
minimum heat demand and overall annual heat demand.
Capital cost is strongly dependent upon physical
characteristics of the resource. In a district heating main
system the financing of the pipe network is generally the
major element in the final cost of heat to the consumer.
Simulation methods enable us to model variations of system
variables such as indoor temperature, flow and pressure in
the system as a function of weather condition with time for
accurate design and operation of district heating systems.
Purpose of this study is to use these simulation models to
analyze district heating system operation during a cold wave.
2
THEORETICAL BACKGROUND OF THE DISTRICT HEATING SIMULATION
Introduction
District heating system is designed to be in operation number
of years. During the operation years some adjustment are
expected as size and type of building and population.
Calculation of estimated energy requirements and fuel
consumption of district heating systems are based on many
factors. It is necessary to take in to consideration all the
variables for accurate design.
Two kinds of methods have been used for the design of
district heating system in Iceland. One of them is to
calculate heat requirements based on size and type of
buildings and other one is to use annual fuel consumption to
estimate the heating requirements of the buildings. The
first method is known to be very time consuming.
Desiqn Demand Based on Type of Buildinqs
In this method it is assumed that the power demand of a
building depends on size and the heat loss characteristic of
buildings. The daily heating requirement of building has
been evaluated for the Reykjavik systems.
Over the years for the Reykjavik heating system the maximum
average daily heating requirement of buildings connected to
the system with direct hot tap water connection:
One story buildings
24.4 W / m3
Two story buildings
22.1 W / m3
Three story buildings
19.8 W / m3
Four story buildings
17.4 W / m3
3
Since these figures represent the average daily requirement,
the maximum hourly demand is estimated to be 30% higher
(Karlsson , 1982).
Design Demand Based on Fuel Consumption
Estimation of annual fuel consumption indicates heat demand
in the buildings. Most of the Iceland people enjoy
geothermal district heating systems, although the houses
outside of the geothermal district heating system are heated
with fuel oil and electricity in Iceland .
At the and of 1985, the 29 district heating systems served
population of 190,000 people, corresponding to 80% of the
Icelanders (Gudmundsson and Palmason, 1987) .
Average building volume per person is 117 m3/ person in
Iceland (Karlsson, 1982). This analysis is limited for the
calculation of annual heat consumption but some information
can be obtained.
weather conditions
Prediction of energy consumption may be difficult as many
variables are involved for a long period. Weather data is
important information for prediction of the heat
requirements . It is necessary to obtain information on the
local climate when the district heating systems are designed .
Main parameters are the monthly mean temperature, annual mean
temperature and the worst cold wave to expect during the
operation time of the system.
It is useful to be able to predict the heating requirement of
buildings over a season or even over a year . For this
4
purpose the concept of the degree day is useful, but annual
(seasonal) degree days are defined as the number of days out
of the year (season) for which the daily mean temperature is
below a given temperature multiplied by the difference
between the given temperature and the mean temperature for
these days, or (Karlsson, 1982).
(1)
where
DD(T)
NT
annual degree days, a function of temperature, T,
the number of days out of the year for which the
daily mean temperature is below T,
TmT = the mean temperature for these NT
z
For determination of the system design temperature it is
necessary to study the available weather data for the area
and to estimate the effects of the worst cold waves on the
inside temperature of buildings. The cold wave is defined as
a period of at least two days for which the outside daily
mean temperature is below the system design temperature
(Figure,l) . The system design temperature must be selected
high enough so that the maximum cooling of buildings during
the most severe cold wave to be expected will not bring the
inside temperature down below a predetermined value. This
minimum inside temperature for which district heating systems
in Iceland are designed often taken as 17-18 · C (Karlsson,
1982) •
5
Cooling of Buildings During Cold Waves
The steady state rate of heat loss of building is given by
the equation
(2)
where
Q = heat loss,
[W]
K1= overall heat transfer coefficient of building,
[W/"C]
Ti- room temperature, [OC]
To= outside air temperature, [OC]
When the heated mass of a building element is mj and specific
heat of the element Cj, the building heat capacity can be
expressed as
(3 )
When the building is heated with hot water radiators the heat
emitted by the radiators is
(4)
where
Kr = combined heat transfer coefficient for all
radiators in the building, [W/ oC.]
Tr = radiator mean temperature, [ Oc . ]
At the steady state conditions the heat flow from the
radiators is equal to the building heat loss . And than this
equation is obtained by combining equations 2 and 4 as
(5 )
(6)
where
Fv : gross exterior walls are in the building, m2 •
During the cold wave the outside air temperature, To, becomes
6
lower than the system design temperature. This will result
in changes of the inside air temperature according to the
differential equation can be written as
or
(7)
where m, kIt k r , and Tr are constants and Ti and To are
changing with time. Now let
where Tg is the system design temperature . The differential
equation (7) is than reduced to the form
(9)
By defining the parameters
(10)
and
(11)
this equation becomes
l/a dT/dt + T
~
b Tk '
(12)
a and b will be discussed later. With this SUbstitution Tk
is expressing the cold wave, that is how much the outside
temperature has gone below the system desi g n temperature. In
a similar way, T is than expressing the drop in indoor
temperature during the cold wave.
7
Approximation of Cold Waves
Three basic type of cold waves are defined. These are
rectangular cold waves, triangular cold waves and sinusoidal
cold waves.
Figure 2 shows that approximation of cold waves.
variation
of the indoor temperature can be calculated as follows
Rectangular Cold Wave
T - bTd (l-exp(-at»,
O<t<t o '
T = bTdexp(-at) (exp(ato)-l), t>to
(13)
(14)
where
a and b are defined previously in equations 10, 11,
Td= minimum temperature or depth of cold wave as
measured from the system design
temperature,
to= length of cold wave .
The minimum inside air temperature is reached at the end of
the cold wave, for t = to'
(15)
Triangular cold wave:
O<t<to/2,
T = 2bTd(at+exp(-at)-1)/ato'
T = 2bTd(1+a(to-T)
- exp(-at) (2exp(at o/2)-1»/at o ' to/2<t<to.
(16)
The minimum inside air temperature is encountered at the time
t
=
In(2exp(atol2)-1)/a,
(17)
and Tmin is,
Tmin = 2bTd(1-1n(2exp(ato/2)-1)/ato).
8
(18)
Sinusoidal Cold Wave
(19)
where
w is the frequency of the temperature oscillation,
~
= w/to
and
(20)
The minimum temperature is
(21)
The cold wave , Td, is determined in such a way that the
degree days for the cold wave measured from the system design
temperature, DD(T g ), is equal to the degree days of the
approximate cold wave type (Karlsson,1982).
Cold wave type:
Rectangular
Triangular
Sinusoidal
Depth, td:
DD(Tg)/to
2DD(Tg)/to
W
DD(Tg)/ 2t o
If none of the above cold wave approximation seems to fit a
given cold wave, the differential equation (9) can be solved
by a day basis trough the duration of the cold wave using the
daily mean temperature as constant throughout the day. An
even better approach would be to use the period between
weather observation
(3 hours at most weather station in Iceland) as a basis for
the calculations of the cold wave effect on the inside air
temperature. Assuming a linear variation of temperature
between observations, the solution to (9) is
T
= Tlexp(-at)+b«Tkl-Tko)t/~t
+(Tko-(Tkl-Tko)/a~t)
where
9
(l-exp(-at»),
(22)
Tl t =
At =
Tko=
Tkl=
inside air temperature at beginning of period,
time measured from beginning of period,
time period between observations,
outside air temperature at beginning of period,
outside air temperature at end of period.
If it is assumed that the outside air temperature stays
constant,
Tkl z Tko' between observations, Equation (22) is reduced to
the form
T =Tlexp(-at)+bTko(l- exp(-at» .
(23)
where
Tl - inside air temperature at the beginning of the
period
Tko= outside air temperature at the beginning of the
period.
Due to its simplicity, Equation 23 will be used in the
subsequent simulation.
Evaluation ot the Building Parameters
Evaluation of the building parameters of a model building the
being described in (Karlsson, 1982). When the hot water
heating systems is operating at conditions other than design
conditions, the German standard DIN 4703 is being used to
define heat load for these conditions. According to DIN
4703,
(24)
The radiator heat load Qo and the radiator logarithmic mean
temperature ATmo above the room temperature are at design
conditions and Q and ATm are the same quantities at some
10
other conditions.
is defined as
The radiator mean temperature difference
(25)
where
Tf - inflow water temperature to radiators,
Tb = return water temperature from radiator
Ti K room temperature.
The radiator heat transmission coefficients are assumed to
vary with the load, according to the equation
( 26)
leads to
Q / Qo = krATm/kroATmo
= (ATm/ATmo )4/3
(27)
When a district heating system is designed for a system
design temperature different from the design temperature for
the radiator heating system, the mean temperature differences
will also be different from that at design conditions
(Karlsson, 1982).
When noting that the relative heat loss from the buildings
equal relative radiator heat load.
Equation 27 becomes
where
Tg = system design temperature, ·C,
Tgo= radiator system outside air design temperature
(= -15 ·C).
11
During the operation Tb is changing with time depending on
outside temperature .
Calculation of Tb is being done by
fixed point iteration using Equation 28, and this equation is
rewritten as
Tb=Ti+(Tf-Tb)/exp«(Tf-Tb)/(Tfo-Tbo»*ln«Tfo-Tio)/(Tbo-Ti0)
*«Tio-Tgo)/(Ti-Tg»3/4).
(29)
Equation 29 enables us to calculate correct Tb by iteration
starting with some initial guess of Tb'
Experience has shown
that this equation is quite stable an converges quickly.
At the system design temperature, Tg , the heat balance for
the building gives
(30)
Two types of building parameters are defined as "b" and "a".
Parameter "b" depends only on the k values while
parameter
"a" depends on building heat capacity as well (Table 1) .
Equations 10, 11 show the values of "a" and lib" from then is
found to be
b = kl (kl+kr ) = 6Tm/(6Tm+Ti- Tg),
a = kl I m b [lis]
a = kl I m b [lis] * 3600 [s/ h] * 24 [h/day
a = kl I m b [l/day]
(31)
(32)
m is the building heat capacity defined in Equation 3 as
m = C/Fv
(33)
normalized on basis of the outside wall area (Table 1).
As an example of these calculations, the most common one
family building in Iceland is used. This building is one
story, about 109 m2 ground floor area and made of reinforced
concrete with 100 mm polyethylene insulation on inside of the
12
walls .
For heat losses from the buildings, the heat transfer
coefficients specifies the following maximum values of heat
transfer coefficients (k values):
k-value
k-value
W/m 2 ·C
W/m 2 ·C
Exterior walls
0.55
Windows
Roof or ceiling
0.30
Doors on ext.wa l ls 2.5
Floor
0 . 30
Air change, 0 . 8/h
3.2
0.29 w/m 3 ·c
The mass of interior walls and floors are based on a mass
density of 2.5 * 10 3 kg/ m3 for poured conc rete and 1 . 5 * 10 3
kg
1m 3
for light aggregate walls.
The spe cific heat for both
poured concrete and light aggregate is assumed to be c
= 0.88
kJ/kg·C
(Karlsson, 1982).
At the usual Icelandic radiator design condition 80/ 40,
-15 ·C,
these values are obtained as,
Tfo = 80 · C
Tbo = 40 · C
Tf = 75 · C
Tio=
20 · C
-6
-8
Tb
ATm
b
31.2
33.1
34. 9
36.9
29 . 1
30.8
32 .4
34
0.524
0. 519
0 . 558
Tgo= - 15 ·C
Ti =
-10
- 12
Tg
0.515
-15
40
36.4
0 . 51
20 ·C
where
Tfo : inflow water temperature to radiators at radiator
design condition ,
Tbo : return water temperature from radiator at design
condition, Tf
Tio
: inflow water temperature to radiators,
inside room temperature at radiator design condition.
Tgo : radiator system outside air design temperature.
13
At the room temperature of 20 ·C for the average Icelandic
one family house the following values are obtained (Table 1) .
ID
=<mi
= 397.28
kJ/m 2 ·c,
(34)
(35)
14
BEAT LOSS CALCULATION FOR THE MODEL BUILDING
Introduction
The model building is typical turkish building selected for
calculating the heat losses. Available data for calculating
the heat loss is obtained from TS 825 (Turk Standardlari,
1985). According to TS 825, Turkey is divided into three
climate zones (Figure, 3). It is required to use different
"k" values for calculating the heat loss in the buildings for
each zone in Turkey .
The district heating system to be simulated is assumed to be
in the first zone. The reason is that geothermal resources
are more frequent in the first zone than the other zones.
This study is made at a hypothetical district heating system.
Data is very limited for the evaluation of heat losses from
the buildings but TS 825 is used.
Description of the Model Building
Most of the Turkish families live in blocks of flats within
the first zone. Mainly these blocks of flats are four story.
The selected model building is four story, and two flats in
every story. Figure 4 which is obtained from TS 825 shows
the plan of flat. This building is about 144 m2 ground floor
area, same roof area. The construction of the model building
consist of reinforced concrete frame, with columns, beams and
slabs. Both the inside and outside finish is of plaster .
The ground floor loases heat to the soil and the top floor
loases heat to unheated space under the roof, which is made
of wooden framework and is covered with tiles.
15
Inside air temperature is assumed 20 · C and outside
temperature is evaluated as -1 · C.
Evaluation of the system
design temperature will be discussed in next chapter.
Heat Loss Calculation Based on TB 825
Throuqh the Exterior Walls
If outdoor temperature is lower than the inside temperature,
heat loss is calculated by this equation according to TS 825.
Q = A*Z*q
(36)
where
Q
specific heat loss,
[W ]
A
heat transfer surface area,
Z
q
heatinq time, [hour)
heat loss, [w/m2)
(m 2 ]
q is defined by this equation
(37)
where
k : heat transfer coefficient,
[W/ m2 · C]
tih : inside air temperature, (RC]
tdh : average outdoor temperature, (·C].
tih = 20 · C and tdh= -l · C are assumed.
k is defined by this equation
(38)
k
where
l/Qi : interior surface thermal resistance, [m 2 · C/W]
l/Qd: exterior surface thermal resistance, [m 2 ·c/w]
l/A : thermal resistance of the building
material, [m 2 · c/w)
16
The usual outside wall is composed of two layers of plaster,
2 cm thick on the outside and 19 cm thick brick as main wall
material.
Conductivity is assumed to be 0.87 Wjm·C for the plaster and
0.45 W/moC for the brick. This results in
l/ai = 0.14
l/ad = 0.05
1/ A =
d1/~h1
+
d2/~h2
+
d3/~h3
(39)
where
d1= 0.02 m thickness of the interior plaster of wall,
~h1
= 0.87 W/m'C thermal conductivity of plaster,
d 2 = 0.19 m thickness of the brick,
Ah2 = 0 . 45
W/m'C,
d3 = 0.025 m thickness of the plaster of the ext erior
wall,
Ah3 = 0.87 W/m'C,
this results in
k = 1.57 w/m 2o c for exterior walls .
Exterior net wall area is found to be for the model building
A = 317.04 m2
and total heat loss through the walls
Q = 10452.8 W.
Through the Doors and windows
k value is taken from TS 825 (Turk Standardlari, 1985, Table
4) for ordinary doors and single glass windows as 5.2335
w/m 2 ·C
( 40)
17
where
tih
~
20 · C
tdh = -1 · c
A = 175.76
k = 5.2335
m2
w/m 2 ·c
and Q is to be found
Q - 19316.63
w.
Through the Root
For calculation of the heat loss to the roof !lA" value taken
from TS 825, Table 3 and roof temperature is assumed as 6 · C.
Q = k A (tih-tdh)
k = l/A + l/ai + l/ad
m2 · C / W (TS 825 Table 3)
l/A = 0.86
m2 'c / W (TS 825 Table 5)
l/ad - 0.1204 m2 ·c / W (TS 825 Table 5)
l/ai
= 0.86
k - 0.671
tih = 20 · C
w/m 2 ·c
tdh = 6 ·c
A
144 m2
and Q is to be found
Q = 1831.7 W.
Through the Ground Floor
The soil temperature is assumed to be 10 ·C .
Q - k A (tih-tdh)
l/k= l /a+l/A
1/a= 0.172 m2 ·C/W
(surface heat resistance of the ground),
(TS 825 Table 5)
l/A= 0,688 m2 ·c/w (heat resistance of slab)
18
(TS 825 Table 3)
k - 1.16 w/m 2 · c
A = 144 m2
Q = 1674.7 W.
The result of the calculation:
Total heat loss from the model building = 33275 . 89 W,
Total volume of the model building = 1584 m3 ,
Design demand of the model building = 21 w/m 3
Buildinq Beat Loss Parameters
Most of the hot water heating systems in the first zone are
designed with 90 / 70 , -6 or o · C in Turkey. Two design
criteria were assumed for evaluation of building parameters
that is 90/70 and 80/40 · C. Design outside temperature of
To= -7 ·C and system design temperature Tg=-l · C in all
cases. So far the model building heat loss has been
calculated according to TS 825. In this chapter the model
building heat loss is being used to calculate the building
parameters.
The characteristic values are obtained for the model building
assuming 20 · C room temperature. Table 2 and Table 3 show
the results for the first zone at outside temperatures -1 · C
and -7·C.
At the design condition, 20 ·C room temperature and -1 ·C
outdoor temperature average building heat load is calculated
as 33275.89 W at the model building according to TS 825. By
assuming same infiltration heat loss as in the icelandic
buildings 0.29 W/m 3 · c, the total infiltration heat loss is
calculated as Qinf = 9646 W. This increases the total heat
loss to
Qtot = 42922.5 W
and design demand of the building to
Qdes = 27 w/m3.
19
DESCRIPTION OF THE DISTRICT HEATING MODEL SYSTEM
Introduction
The model system consist of qeothermal well as a heat source,
well pump, a storage hot water tank, a pumping station, for
transportation of the energy, the main transmission pipeline
and the energy distribution network.
The model system has been designed as typical part of the
Turkish city as the block of flats are concentrated on both
side of the street. The trunk branch of the pipeline is in
the main street in approximately 2 km distance (Figure 5).
The trunk branch is divided into sub branches which are
connected the house connection branches. The radiator design
conditions for buildings heated with conventional fuels are
usually 90/70 ·c in Turkey as previously mentioned. This
result is what is most common in older buildings, but
especially where geothermal heat can be found buildings are
now designed with 80/40 · C radiator systems . For this reason
some part of the model system has been designed as 90/70·C
and the other part is 80/40 ·C. The return temperature of
the hot water and the hot water demand are ev aluated for two
parts separately.
Design heat load has been calculated as 27 w/ m3 for the model
building. Estimated heat load demand for the system has been
calculated based on the design energy demand. Figure 5 shows
the city and the distribution system.
Geothermal wells
Geothermal wells are one of the important items in geothermal
district heating systems. The characteristics of the wells
and the reservoir performance affect directly the cost of a
district heating system.
In this simulation, the well will not be considered, but only
20
the flow from the storage tank to the system.
The Main Transmission Pipeline
Energy is transported from the heat source to the residential
region by the main pipeline with length of 2 km. It is
assumed that steel pipes are used on the pipeline and all the
pipes are insulated with rock-wool. Expansion joints are
used for thermal expansion at the horizontal direction. The
fixed points are constructed before at every expansion joint
for preventing different directional moving of the pipeline.
The Network
The network is assumed to be Dade from steel tubes isolated
with polyurethane. One supply pump pumps water from the
storage tank to the system .
weather Conditions
Real weather data is taken from Virkir, (Virkir 1987), who
obtained it originally from the Meteorological Office in
Denizli, Turkey. The observation period is 1957-1980, and
this has been used in this report for evaluating the system
design temperature (Table 4). This Table shows that the
minimum outside temperature is -11.4 ·C , the maximum outside
temperature is 41.3 ·C. The Dinimum average monthly
temperature is 5.5 ·C while the maximum average monthly
temperature is 26.6 · C.
The steady state heat loss calculation of the model building
has been done according to outside temperature at -1 ·C. In
fact of the real weather data shows minimum outside
temperature is -11.4 ·C . At this condition it is possible to
evaluate the system design temperature and the estimated heat
loads with DD day of the months. In this report estimation
of system design temperature based on the Karlsson method,
which evaluates the system design temperature based on
variation of indoor temperature during the cold waves lower
21
than the system design tempe rature .
Equation 23 is defined previously, which defines building
cooling during a cold wave, when assuming that the outdoor
temperature stays constant between the weather observations.
The room temperature is 20 ·C at maximum heat load, which is
defined to occur at system design temperature.
It is commonly assumed that a minimum indoor temperature of
17-18 ·C is acceptable. To obtain realistic weather data for
a Turkish town in the first climate zone, available
meterological data from Denizli, Turkey was used (Figure 6).
As this data contains only average temperatures, temperatures
measured at three hour interval in the city of Reykjavik,
Iceland during the year of 1981 was considered to describe
plausible temperature variations. In order to have the cold
wave in January 1981 in Reykjavik to be corresponding to the
coldest wave to expect in climate zone 1 in Turkey, these
variations are multiplied with 1.5. Follow this
TaveO+ (TOR - TaveR)
*
1.5 = Tosim
(41)
where
outside temperature
average temperature
Tosim: simulated Denizli outside temperature
Subscript 0 and Rare Denizli and Reykjavik.
Figure 6 shows the simulated weather data together with the
linearly interpolated monthly weather data points from
design.
Evaluation ot the system Design Temperature
Table 4 shows that minimum outside temperature as the number
of days with outside temperature under -10 ·C or lower is
only 0.2, 3.5 days with outside temperature lower than -5 · C
and 9 days with temperature lower than -3 ·C during the
observation periods. At this point the Karlsson method
22
approaches the problem differently by calculating how many
degrees the room temperature will be reduced during the cold
waves. The minimum room temperature is accepted as 17-18 ·C.
Equation 23 describes reduction of the room temperature
during the cold waves. Equation 23 is
where
T = drop indoor temperature below 20 · C,
Tl = inside air temperature at beginning of period,
t = time measured from beginning of the period,
Tko= outside air temperature at beginning of period,
a and b building parameters are defined before.
Figure 7 shows the values of the T and result of the dynamic
heat loss calculation for the first days of January. In this
calculation it is assumed that outdoor temperature always
constant for 3 hours between obse rvation. On the Figure 6 it
can be seen that the worst cold wave to expect occurs in the
first days of January . This cold wave is so close to the
lowest measured temperatures that it can very well be taken
to be the worst cold wave to expect during the system
operation . When the inside temperature drop is 3 . 9 · C as
allowed, the system design temperature is -l · C and minimum
outside temperature is below system design temperature. At
this condition heat loss from the model building is 42922.5 W
at this system design temperature.
Figure 7 shows the January cold wave and the calculated
variation of the indoor temperature.
23
SIKULATION OF TRB KODBL DISTRICT BBATING SYSTEKS
Introduction
So far, theoretical background of the district heating system
has been discussed, heat loss calculation of the model
building, the building parameters have been calculated for
the model building, the system design temperature has been
calculated and simUlation weather data evaluated for carrying
out real data for calculation system design temperature of
the model.
The purpose of this chapter is to follow the indoor
temperature profile when the system dynamic energy demand is
changing with time depending on outside temperature and also
to calculate hot water demand.
Description of the Work
Design of pipinq Network
In order to be able to perform a simulation, piping network
was designed the system shown in Figure S. Main design
criteria was to keep pressure loss between o.s and 1.0 bar/km
(Karlsson, 1982). Summary of the piping network design is
found in Table 5. According to this design system pump was
chosen to have characteristic of
( 42)
where
H
pressure head, [m]
Ho : pressure head at zero floor, [m]
[m 3 /s]
Q
flow,
k
pump constant.
24
The chosen values are
Ho
120 [m].
k = 3.3 10 5 [ms/m 3 ].
Schematic of the simulated system is shown in Figure 8.
It is to be noted that all pressure meter output will be in
meter of piezometric head.
simulation of the System
This system description was input to a computer simulation
system of the University of Iceland. This program is named
SIHEAT and is made available for this project by the
University of Iceland-Nordic council district heating
research programme .
SIHEAT simulates flow and pressures in the network as well as
indoor temperature in each of the buildings. The thermal
dynamics of the building are calculated in same way as in
Equation 23. The flow restriction through the building
radiators which will give indoor temperature of possible
20+/-0.05 ·c is than calculated. Minimum flow restriction of
the radiator is calculated according to radiator system
design temperatures, assuming a required minimum head of
15 rn, or
klmin = AHminl~es
(43)
where
AHmin : 15 m
This is considered to correspond to the lack of heat
situation, where all radiators valves are fully open. These
calculations are repeated until system flows have become
stable for every time step.
25
CONCLOSIONS
The result of the simulation are shown in Figure 9, 10, 11
and 12. Network flows durinq the January cold wave are shown
in Figure 9.
Figure 10 shows gage pressures at the points
where pressure meters are located. From Figure 10 is can be
seen that the farthest and highest points in the system
(nodes E and C) have only about 17 m pressure head at maximum
load situation. This confirms our pump selection as quite
acceptable.
It is interesting
to note differences in the
indoor temperature variations as shown in Figures 11 and 12.
In Figure 11 the indoor temperature variations for the 90/70
·c systems are shown, and they are similar for all buildings,
indicating that the distribution network is not a limiting
factor in the heating of buildings. On the other hand is
substantial variation of the indoor temperature variation of
the 80/40 · C systems, indicating that the network is limiting
the heat flow to the farthest buildings. Also does this
network limitation more than compensate for the better
radiator system, the indoor temperature drop is bigger for
the 80/40 · C systems than for the 90/70 ·C systems.
Despite of this, the simulation shows than actual indoor
temperature variation is less then what was anticipated by
the calculations of the system design temperature.
The final conclusion is then that the simulation shows that
when the pump is selected so that lowest pressure in the
system is acceptable (about 17 m head), the indoor
temperature drop is considerably less than the maximum
acceptable . Therefore the thermal performance of this system
is overdesigned when the system is just fulfilling minimum
pressure criteria.
26
ACKNOWLEDGEMENTS
The author wishes to express his special thanks to Mr . Pall
Valdimarsson, the author's adviser, and Dr.Jon-steinar
Gudmundsson, the director of UNU Geothermal Training
Programme for their invaluable guidance and comments during
the training course and the writing of the report . Thanks
are also expressed to Prof. Valdimar K. Jonsson, University
of Iceland, Dr. Oddur B. Bjornsson, Fjarhitun Consulting
Engineers Ltd for their valuable advice, information and
discussions. The Turkish authorities are thanked for
granting leave during the period of the fellowship . Finally
the author would like to thank everybody who has presented
lectures or given assistance to the author during the whole
training programme.
27
NOMENCLATURE
A
a
radiator surface area, (m 2 )
= (k r + kl)/m building parameter
b
kl/(k r + kl) building parameter
C
heat capacity of items inside a heated building, (kJ/K)
Cj
specific heat of item j inside building,
Cw
specific heat of water,
(kJ/kg.K)
(kJ/kg.K)
DD(T): annual degree days below temperature (T)
Fv
gross exterior wall area of building,
(m 2 )
Kl
overall heat transfer coefficient of building,
Kr
combined heat transfer
(WjK)
coefficient for all radiators
in building, (W/K)
k
radiator heat transfer coefficient, k/ (m 2 .K)
kl
normalized heat transfer coefficient of building
normalized radiator heat transfer coefficient
L
length of pipe, (m)
m
normalized heat capacity of items inside building
=
(C/Fv )
mj
mass of item j
m
mass water flow rate,
NT
number of days in year with mean temperature below
Q
heat loss from building or pipe,
T
temperature, (ec)
Tb
return water temperature from radiators, (·C)
Td
depth of cold wave below system design temperature
Tt
inflow water temperature to radiators,
Tg
system design temperature,
inside building,
(kg)
(kg/5)
28
( · C)
(W)
(·C)
eT)
Ti
room temperature,
( · C)
Tk
To - T
Tm
annual mean air temperature, (·C)
TmT:
mean temperature for NT days in year,
To
outside air temperature, ( · C)
Tr
mean water temperature in radiators, ( · C)
ATm:
logarithmic mean temperature differences, ( · C)
t
time
to
duration of cold wave, days
a
surface heat transfer coefficient,
A
thermal conductivity, (W/m K)
A
thermal resistance of building material,
~
density, (kg/m 3 )
~
phase angle for sinusoidal cold wave = tan- 1 (wj a)
w
frequency of sinusoidal cold wave = w/to
29
(·C)
(wjm 2 · c)
(m 2 /w · c)
REFERENCES
Diamant, R.M.E. and Kut D., (1981): District Heating and
Cooling for Energy Conversation, The Architectural press,
London, 464 pp.
Harrison, R. (1987):"Engineering Economics of Geothermal
Heating Applications," Report 5, Geothermal Training
Programme, Reykjavik, Iceland, 195 pp.
Turk Standardlari, (1985): "TS 825 Thermal insulation in
Buildings,1t Report TS 825 Turkish standard Authorities, in
Turkish, 31 pp.
Karlsson, To, (1982-4): "Geothermal District Heating the
Iceland Experience, " Report 1982-4, UNU Gethermal Training
Programme, Rekjavik, Iceland 116 pp.
Gudmundsson, J . S. and Palmason, G. , (1987):
11
The Geothermal
Industry in Iceland," Jounal of Geothermics, Vol. 16, no 5/6,
pp. 567-573, 1987.
Virkir, Consulting Group LTD . , (1987): "city of Denizli
Turkey Geothermal District Heating," Prefeasibility
Report,sidumuli 1. 108 Rykjavik, Iceland.
30
Table 1 - Characteristic values for an average one story
building Icelandic home (Karlsson, 1982) .
kl
W/m 2 . o C
Net floor area, m2
Cross exterior waii area, m2
.-
Window!
Doors on exterior walls
0 . 2185
0.0609
0.7206
3.2
2.5
0 . 55
floor (outer section)
Floor (inner section)
0 . 9323
0.2704
0.6619
0.3
0.3
0') ' 15/(20-T g '
House volume
2.5641
0 . 29
;"'e Net
LoN
-< •
"•
N
~
109.55
127.30
exterior walls
Roof (ceiling)
~
•E
"o
z
~ N Poured concrete parti tions
e e
~ _Light aggregate partitions
~
~
..,
E
Poured concrete fioor
0.0248
54.56
0.0703
92.80
249 . 92
0.1136
31
Table 2 - The characteristic values at 20 · C for the model
building.
Net floor area , m2
144
Gross exterior wall
area, m2
492.8
Heat loss parameters
Areas
Normalized
Areas
Windows
175 . 7
0 . 356
5 . 2335
317
0.643
1. 57
Roof (ceiling)
144
0.136
1.16*14/ (20-Tg)
Floor
144
0.136
1. 45*10/ (20-Tg )
Net exterior
walls
Heat capacities
Volumes
m3
Normalized
Volumes
m3 /m 2
House volume
1584
0.381
heat capacities
kJ/ m2
Poured concrete
partitions
mi
Normalized
14.3
0 . 029
54.4
98.28
0 . 769
254 . 3
0.263
491.8
Light aggregate
partitions
Poured concrete
129 . 9
floor
Note
normalized values are normalized on basis of gross
e x t erio r wall area.
32
Table 3 - Evaluation of building parameters for the model
building at outside temperature of -7 · C.
Tg
1
Tb
57.37
63.37
68 . 48
71.93
73.74
ATm
b
a
45 . 63
48 . 98
51. 73
53.52
54 . 42
0 . 706
0.699
0.692
0.681
0.668
0 . 706
0.639
0 . 642
0.648
0 . 657
m
800.4
800.4
800 . 4
800.4
800.4
4.18
4 . 147
4.118
4.093
4 . 072
39168.5
42922 . 4
46676.3
50430 . 2
54 1 84.1
k1
Q
'c
·c
Tf
75
Ti
20
Tbo
20 · C
1
Tg
-1
Tfo
-3
90
·c
70 · C
Troof: 6 · C
Tbo
-1
-3
-5
-7
-7 · C
10 ·C
Tground:
Tgo
-5
-7
Tb
ATm
b
31.69
34 . 22
36.89
39.68
42 . 57
27 . 97
30.15
32.28
34 . 36
36 . 40
0.595
0 . 589
0 . 583
0.578
0 . 574
a
0.758
0.759
0 . 761
0 . 763
0.715
m
800.4
800.4
800.4
800 . 4
800.4
4.18
4.147
4 . 118
4.093
4.072
39168 . 5
42922.4
46676 . 3
50430 . 2
54184.1
kl
Q
·c
·c
Tf
75
Ti
20
Tbo
20 · C
Tfo
80 · C
40 ·c
Tbo
Troef: 6 · C
-7 · C
Tground : 10 · C
Tgo
33
Table 4 - Weather data for Denizli, Turkey (Virkir, 1985).
t
ENleM Df~'ECESi:) T ' 4 T
eOYL~" hERECfSi;2~ 0'
RASAT SURESl:l<;,1-1'9S0 (2"
ST ASYON AOI: OHI i {I,.
VUKSEKlicl: 428 H
1STASVO~
,
1---------------------------1-------I
•
1\
1
HETEOROLOJ'K ELEHANIN AOI
1---------1
' '
,
I
1
2
3
"
1--------------------------1---IOUALU!A,
1I
SICAK Ll K
5 .. 5
6.~ ' ~ . ~
1-----------,,-----------------1------16 .. 8 19_0 2i.7
101lHll"A SlCAKUGIN>5 .. 0
C1.DUCU C'UNLER SAYlSI!
I ------------::--------~
'OATALMU S(CAI<LIGIN>lO.O OLDuGU c;.UNLER SAYlSt!
1---------:-------------------1
IEH Y~'t(.SEK SICAKlIK
1
4.3
22.6
6.2
I
~
23.8
11
26.6
9
25.~ ' 21.5
-
30_0
31.0
31.0
30 .. 0
31.0
28.2. 21.e
2'5.8
30.9
3C.0
31 .. 0
3l.0
30.0
2'1.9
21.0
3-11 14.78 31.11 12. 70 30.80 210 . 73 20.7] 25.'8 11.72.17.60
3 . '9
29 . 0
35.2
31.0
:!'iI .. 2
41.3
41 .. 2
31 .. 0
15.71
____
1
121.11
'31.(1
--
i
1 ..1
14.2 , 11.4
29.9
.
15.8
7
29.9
_I
'7.'1.
26.6
2f2.71
1
_ ~1.21
'.
I
21,~:-:;:-;;'
1-----------------------·
-----1----------IEN YUKSEIC STC.lKlIG1N>30.0 OlOUGu GUNl.ER SAY(SII
0.0
0 .. 0 ' 0.0 .'
0.6
5.4
18.'
28.1
21.8
13.0
,, 1.9
:0 .. 0
0.0'
'lI,:2t '
1Ft. viiKsEK SIC.lKllGIN>25.0
5.3
18.4
21 .. 5
30 .. 8
30.9
U_3
12.5
(;.6
·0.0
152..11 ;
0.0
0_0
(1.0
0.0
1---------------------------1--w
6
33 .. 5
23.8
1---------------------------1-. --I EIt vi:.cSEK SICAKLICIN TARiHt
5
14 .. 1 , 19.2
1-----
- - - - -___ ,
I
I,
la "
11
,12
'YIlLIKI
AY l A R
---
OlOUGU CUHlER SAYlslI
0 .. 0
0.0
0.10
t'
1---:-:--------=--------_---:.------1
IEN 'tUKSEK SICAKLICIN(O
DlOUCU CU"LER SAY[SI I
0.3
0 .. 1
0 .. 0
0.0
0.0
1-------------------------------1------IfN DUSUK SICAKl(K
.
1 -10.5 -H .. 4 ":".0 -1.7
2.1
1----------------.,-------------1
----tEN DUSUK SlCAKLlGU'i TARtHi
.. I I~.64 'lI. 65 1.6112.4914.80
1---------------------------------1
IEN DusiiK SICAKLlC(N<O .
ClDUGU CUNlER SAYISI I
10.5 . 6.9
leN oU$UIC SICAKLlGIN<-l.O
OlDUGU GUNLER SAYIS[j
1.6
. OlDUGU CUNLER SAYlS11 '
OlOUCU CUNlER 'SAY(SII
'lI.0
12.6
ly
9.62
4.64
2.6830.70
-11.41:
-8.11
-----1
21.67 23'.n '1.2.H!'
--'--I
0.0
l.~
0 .. 0 ·
0.0
C.Q
o.c
0 .. 0
1.0
,.4.0,
21:-;;1 '
0 .. 0
0 .. 0
0.0
0.0 ,
0.0
0.0
0 .. 5:. 2.3'
~;:-;1.
_______________ 1'
0.0
0.0
o .. C
C. O
0.0
0 .. 0 '. 0 .. 3
0. 0
. 5.6
2.2
0 .. 0
0.0
6.l
4.3
1. 2
1--,, ::--------::---------::---;:--------1----. ------
0.0
lE'" DUC;uK '\lCAKLIGli1<-) .. 'J
40.1
3.1
o.s
0.0
-------
1-------------------------------1·-----------------SICAlClTCIN<-2 .. 0
t;
- 0_8 : -4 .. ' ~10.4
0 .. 0
0.0
ou:;U)(
___
I'
0.41:
c.o
0 .1
!EN
0 .. 0
0.0
3.4
1-------------------------------1----------
6.6
-----0.0
o.c·
I'
5.!'
.
1.0 :
2!.Ct
_1
I
9 .. 01:
1------------------------------1----------" 0.1 0.': !!.41·I'
IEN oij$i:1< STC.1.KLlCIN<-Io.O
OlDUCU CUNLER SAYISll
, 2 .. 8
1.8
0.3
0 .. 0
0.0
0 .. 0
0.0
C.C
0.0
0 .. 0
1--------------------1-----------0.0-~ · .
' J .. H1
lerl OVSUIC SICAKt.l1ilN<-5.0 , OlGUGu eUNlER SA.,tSII
2.0
1.1 ' 0.1
0.0
0.0
0 .. 0
o.c
c_c
c.:
O.CI :· 0 .. 3 ~
1----------------------------------1----------------t
IEN OU~U)( SlCAKlI"GIN<-lO.O D.lDUCU C'UNLER, SAYISI!
'.1
0.0
0. 0
0.0
0 .. 0
0. 0
0.0
0 .. 0
O.C
C.. O
0.0
0.0
0.21
1------------------------------------1-------1
IHo! oiisiil< S(CAKl!GHnlo.o
OLOUGU CUNLER SAYlSl1
(.6
0 .. 8
2. 3
11.8 25.3 2et.9 31 .. 0 :HA 28 .. 7
11!.9' 6.0 ' 2 .. z~·· u,.~!
1--------------------------------------1-------------------------------_
__________________
1
IEH 0'U5ij)( SICAKlIr.n>20.0
OLDUGU C'UNlER SAY1SIj
'.0
0.0
0.0
0.0
0_1
2 .0
'1.3
6.,.1
0.3
C.C. Cl.Cl
0.0
17.8\
1---------------------------------1---------------_____
' __ "-_,
Note :" AYLAR" means "months"
ll
11 ORTALAMA SICAKLIK" means "average temperature
EN YUKSEK SICAKLIK" means tlminimum temperature"
" EN DUSUK SICAKLIK" means "minimum temperature"
tI
Table 5 - Summary ot the Pipe syate. design.
Pipe House
Sum
SUd
Pipe
run
demand
flow
die ••
volume
If
'"
Vel. Pipe
Reynolds Pres s ure Pressu r e
lengt.h number
•
l/a
drop
aVa
d r op
bar/ kJII
G1-G
3500
94500
0.49
35.9
0.48
320
36337.6
2.990
0 . 9)4
G2-G
6000
162000
0.14
53.0
0.38
170
42194 . 7
0.761
0.448
13000
351000
1.82
68.8
0.49
lOO
70426 . 7
1. 44]
0 . 481
8000
216000
1.12
52.5
0 . 52
250
5 6 795.4
2.085
0.8H
28000
156000
3 . 93
77.9
0.82
lOO 1JJ968.6
]. ]].
1.110
£1-£
3500
94 5 00
0.49
35.9
0.48
320
36337 . 6
2 . 88 3
. 0 . 90 1
E-O
6000
972000
5.05 102.3
0.61
600 131162 . "
2.931
0.489
O-C
65000
1755000
9 . 11 105.3
1.05
lOO 230013 . 9
2.371
0 . 59]
J1- J
6000
162000
4.84 102.3
0.59
275 166770 . 2
1.661
0.604
J-,
8700
234900
7.01 105.3
0.81
'50 234927 . 4
4 . 239
0.942
kl-k
3500
94500
2.82
68 . 8
0.76
120 144651.3
1.281
1. 0 6 7
1.00
l50 360897.0
] . 446
0.985
1.18 2000 383452.8
18.]27
0. 9 16
G-F
Fl - F
F-E
'-C
16500
445500 13.30 130.0
C-B
82500
2227500 22 . 42 155.4
Hot.a: valUes between GI-G and D-C represent. new design of t he p ipe s ys te";
at 80/40 • C. while JI-J represent a exi s t.ing design at 90/70
35
·C .
Dale
o
04 .02 . 69
O~ .OZ , 6'
oa,Ot .G9
OT.02 . S'
08.02 .tS.
09 .02.69
~
.r-
- 2
~
J
- 4
- I;
}l
~
- 8
~
1:
"~
-10
~
,r
- 12
J
-14
- 16
- 18
t-
U-
r1
Figure 1 - Observed temperatures in Reykjavik during a
severe cold wave (Karlsson, 1982).
36
rdr-------------------~~----~
(a)
10/2
I.
(b)
r.---------------~'~.~~~~----------------~~~~
I
I
I
I
I
rd - --- -- --- -
-
I
"-........ I
-- -
._L __
(c)
Figure 2 - Cold wave approximations (Karlsson, 1982).
37
.,
"
~
.-.- .-;::::; .......
'""~
..,
'"
)L\
a
"
\'0
N.~.hit
lI.
.,w
tzZl
t::=I
"m
..
I . sOu;[
1 . 8CLGf
1'. 80LGE
HA RirAOA I. BOUiE !~INOE OLUPO~ FU.KIMI IQ,OO M. ,NI,N \srUNOE
OLAN YERLER. 11,_ 89LG.EOE,' HARITACJ. 11. BOLG ~ IC IHq; ,a.uPTA
RAI(/toI'I I!loq M.NtH USTUHOE OLA'I'YE:=;LER m..SOLGE 1 ~IHOf
KABut EOiU RlE'R. JD:, BOLGEDE ~Oi..U;:-
OI..AH YFRu.~,,~.eOLGECf; ~BOlGEaE
ALt lHOA Ol .A1oI vFP.1 fR
FKlL_
IS I ETK ILERINDEN KnRlI l"'"
V(Wii"OEI' liipv.i ·'E ;"Li .. "r
Figure 3 - Climate zones in Turkey (Virkir, 1985).
Note
"BOLGE" means "zone".
T.80LGEOE
R;'K~; 1=0 M. Hlli 1.:"'Tt~!
OLUP
KABUl
~~IMI IOOM.NIN
EOtLIRLER.
r-FLERI -IARITASI
'1, 00
r
9.00
living
I
Bed
room
room
I
Kitchen
I
2/
Bath
',OD
1',00
Figure 4 - Plan of the model building layout
(TUrk Standard l arl , 1985).
39
I
room
G2
1 3500
I
I
G
-SOo
!,2500
~- - ~,
/1 ~
foo
/
/ ~~~~I
:"I
<~"~t
,!J ~
I ."
,
o
~
~
1
'>
<>0
0
""o
~
£1--- -------
._...
--- -
_----
..
2900
...
--
-
Note:
0
-D
Numbers indicate buildings volume, m3 .
Pump station and storage tank are located at Node B, and
distance C-B is approximately 2 km .
-
Scale is approximately 1:5000.
The nodes J, Jl, K and Xl have 90/70, -7·C radiator systems.
The others have 80/40, -7·C · systems.
A futUre connection is assumed in Node D about 20.10 3 m3 ,
2.8 lis flow.
Figure 5 - Layout of the model system.
'-
-
(
'
--c
//
jj B
"~----------------------------------------------,
4lJ
30
.20
..
....
10
o
1111 I 11
-10 -j
-.20
"
I
1
31
It
.,
ii
1.11
11f1
1.,
.211
Z41
Z'11
301
331
3.,
Figure 6 - Weather data-actual maximum, minimum, average values for Denizli
Turkey together with simulated temperature.
1
o
,
,\
-.2 -8 -4 -1
-0
\
1\
~
'V
1/1
Vv
\
1/\
.
V
-
N
..., -7
-
...,
o
.,
.,
t
z
'
:I
4
6
B
.,
B
11
.,
.,
.,
to
11
tZ
Figure 7 - .Temperature variation durinq a cold wave.
outside temperature below system design temperature,
drop of indoor temperature.
B
/ AII I
Figure 8 - Shematic of the simulated model system.
17
l'
1fl
14
13
1Z
11
10
,
,
,
7
......
fl
4
3
Z
1
,
0
0
1
Z
3
4
6
7
B
,
Figure 9 - System mass flows.
mass flow in pipe C-B,
mass f !ow in pipe C-K for 90/ 70 systems,
~_
masstlow in pipe
c-o for 80/ 40 systems .
10
11
1Z
.100
,.0
-
1'10 180 1110
.'"
11S0
-
140
-~
180
1.10
110
100
H
f1,
V'
-~
~,~~
110 '10 80 ISO 40 80 ao 10
o
....::..
p~
IV
~
'"'q
\t;,
'-
~
l~
1:=
1.,\
\..,
t\
'-
\,
note :
b
gage head at node
gage head at node
gage head a t node
0
.,
.,
1
.I
'-,..
.. ".
3
~
.,
6
..
~
"
8
Figure 10 - Simulated system pressures.
'1
11
gage head at node
•
10
11
1.1
C,
J,
G,
E.
ZO.4
ZO.3
ZO.z
ZOO,
zo
.".Il•
"
.'"
' • •7
".11
' •• 6
' •• 4
".3
,•.,
,i.z
Figure 11 - Simulated indoor temperature for the 90/ 70 systems.
ZO.3
"T""---------------------------.,
ZO""
ZO.1
ZO
.
19.9
-J
19.8
19.7
19.11
19.6
11 I I I1 Ii jl i i 11 i i () jl i i i i I i i ",!ill!11 i 1I I1 I1 Ii ii i I1 !!IIIII ill I i' I i Ii ji i Ililil) ii ji i ii i i i I
Figure 12 - Simulated indoor temperature for the 80/40 systems.
j
i i. i ii
ill